Infants usually breathe through their nasal passages. However, during crying or in the event their nasal passages are blocked, infants may breathe through their oral cavities. Mechanical resistance suffocation takes places when respiration is interrupted if these passages are both blocked externally by an object. When respiration is interrupted, CO2 levels in the blood rise. The body's response to this elevation in CO2 levels is to attempt more rigorous respiration. If the agent of suffocation is not removed, the incident may be fatal after two or three minutes. Further, breathing CO2 or other dangerous gases may be a possible cause of sudden infant death syndrome (SIDS). Currently available garments do not adequately address mechanical resistance and buildup of CO2. Although the exact causes of SIDS remain unconfirmed, overheating is another suspected cause. Overheating may be caused by over-bundling, too much bedding material, or the wrong kinds of materials in an infant's bedding.
Additionally, some infants sweat heavily during the deepest part of their sleep cycles and can wake up wet from the accumulation of sweat. Babies spend more time in the deepest part of the sleep cycle than do children or adults, and are therefore more susceptible to waking up wet. Heat coupled with accumulated moisture can be a cause of heat rash and/or prickly heat. Currently available garments do not adequately address overheating and sweating. Therefore, improvements are desirable.